This invention relates to a pump impeller for pumping a coolant and particularly for a water pump for cooling an internal combustion engine.
Water pumps for internal combustion engines are well known and are present in the larger internal combustion engines. A widely used water pump generally includes an impeller mounted within a housing. The impeller includes a plurality of spaced vanes secured on a round base. The impeller is secured to a drive shaft and is rotatably mounted within the walls of a pump housing. The housing includes an outer closure wall and a shroud over the outer ends of the impeller vanes. A one-piece fully enclosed and double shrouded impeller has been disclosed. However, the system of manufacture is expensive and involves a complex procedure requiring a special high maintenance die unit with a timed and multiple pull action such as found in a camera shutter. An alternative common impeller is a two-piece assembly in which a separate shroud is attached to the vanes of the impeller by a separate means, such as chemical bonding, sonic welding, or a mechanical connection. A one piece impeller with an integral shroud has been disclosed with a special arrangement and location of the shroud.
The water pumps for internal combustion engines generally operate in a high temperature environment. A seal unit is mounted with a bearing to the shaft at the base of the impeller. Cooling of the seal unit at the connection of the impeller shaft to the pump is significant. This requires special construction of the pump unit to maintain a long life assembly with minimum maintenance.
In summary, the prior art plastic impellers involve costly manufacturing procedures which involve costly equipment and various procedures or the case of forming separate components with separate bonding of the separately bonded areas present areas of possible failure and should provide seal cooling means. The present systems do not therefore provide a structure which permits the manufacture of a relatively simple structure for controlling the volume of water flow and efficient seal cooling.